Sewing machine with looper thread retainer



'Marh 21, 1961 R. H. LUKINS 2,975,737

SEWING MACHINE WITH LOOPER THREAD RETAENER Filed July 3, 1957 5 Sheets-Sheet 1 FIG.|

R. H. LUKINS March 21, 1961 SEWING MACHINE WITH LQOPER THREAD RETAINER Filed July 3, 1957 5 Sheets-Sheet 2 m OE March 21, 1961 R. H. LUKINS SEWING MACHINE WITH LOOPER THREAD RETAINER Filed July 3, 1957 5 Sheets-Sheet 3 March 21, 196 R. H. LUKINS 2,975,737

SEWING MACHINE WITH LOOPER THREAD RETAINER Filed July 3, 1957 5 Sheets-Sheet 4 R. H. LUKINS Match 21 1961 SEWING MACHINE WITH LOOPER THREAD RETAINER Filed July 3, 1957 5 Sheets-Sheet 5 dmartest o This invention relates to sewing machines provided with one or more needles cooperating with one or more loopers, preferably though not necessarily of the four motion type, to form stitches of any of the types designated 401 through 406 and 601 through 606, in accordance with the Federal Specification, and variants thereof.

In the formation of certainof thesestitches, cover thread laying meansis required in addition to a plurality of needles and one or more loopers.

It has been found that in the formation of stitches of the character indicated by theconventional devices, and particularly in a machine having a looper or loopers operating across the line of feed in seizing and shedding loops, there is frequently a tendency to skip a needle thread loop. This is due to the fact that the needle thread loop is prevented from opening out properly to permit it to be entered by the looper at the appropriate point in the cycle. It has been found that this results from the twisting, choking or other distorting action upon the needle thread loop caused by the looper thread loop of the preceding cycle, which is at this time looped around the needle. I

A primary object of the invention has been to provide a simple but effective looper thread loop retainer to prevent the twisting, choking or otherdistorting action thereof on a needle thread loop. For this purpose, in the preferred form of the invention, a needle-like retainer is mounted on the needle bar in appropriate relation to the regular needle or needles and is given the same move' .ment as the latter, The retainer is passed through the looper thread loop along with the needle or needles and is arranged to prevent the tightening of a loop of the looper thread around any thread carrying needle. This has been foundto eliminate skipping, of needle loops.

may be applied to machines having a two-motion looper or a plurality of such loopers.

Other objects, features and advantages of the invention will appear from the detailed description of the illustrative embodiment of the same which will now be given in conjunction with the accompanying drawings, in-

which Fig; 1 is a side elevational' view of a port-ion of a feed ofi-the-arm machine to which the invention has been applied;

Fig. 2 is an elevational view of the needle head of the machine as seen from the right in Fig. 1;

Fig. 3 is atop plan view of a throat plate provided on the arm of the machine;

Fig. 4 is a detail view, partly in elevation and partly in section throughthe work supporting arm of the ma chine taken transversely of the axis thereof, looking toward the left in Fig. 1;

Figs. 5-13, inclusive, are perspective views showlng the stitch forming devices of the machine at different points in two cycles of operation of the latter; and

1 Figs. 14 and 15 are similar views of the stitch forming devices at two different points in a cycle of operation with the looper thread retainer omitted.

Referring now to 'Figs. l-4, inclusive, the illustrative machine is shown as being provided with a frame having arm 11 which at the left end carries a forwardly extend An importantwadvanta-ge of the preferred-form'of the invention is that it ,achieves the desired purpose Without the addition of any special linkages or operating devices. A further advantage is that the retainer serves to pro Vida extra looper thread ineachstitch and thus forms a smoother seam and more uniform stitches.

positionedin line with the needles and is disposed just beyond the fartherrnost needle, i.e., the one whose thread loop is last entered by thelooper' on its loop'seizing'niove: ment. Special advantages of the invention ,are derived from its applicationto a machine of-the character "indic-ated. .It should be understoodghowever, .that theinvention may advantageously :be applied to other types of machinesincluding, forexam'ple, flatbed machines 70 having one or more needles and. a' gcooperating'fourr motion looper or. a plurality of suchloopers} Also, it

ing needle head 12. At its right end (not shown) the arm 11 has a downwardly extendingportion from the shaft extending longitudinally of the arm 11 and suitably journaled therein serves to supply power for the operation of the various mechanisms of the machine. I

Through appropriate connections from the indicated shaft;

a needle bar 15 is reciprocated vertically in the head 12 within suitable bearings provided in the latter. A needle clamp-16 secured to the lower end of the needle bar 15 serves to retain four thread carrying needles 17. These are reciprocated from the position indicated in Fig. 1 i

to a position in which the points of the needles are below the worksupport'ing surface of the arm 13, as indicated i in Fig. 4. Screws 18 .or the like, serve to retain the needles in the clamp 16. As shown in Figs. 1, 2 and 4, the needles are arranged in a common plane transverse to the axis of the arm 13 and they extend downwardly to progressively greater'extents so that their points are in stepped relation. The arrangement is such that the needle toward the front of Fig. l and toward the left of Fig. 4 extends downwardly to a lesser extent than the- Extendnext adjacent needle, and so on for the series. ing longitudinally of the arm '13 is a looper shaft 19 to which is imparted a longitudinal or axial movement for needle avoid purposes and rocking movement for loop seizing and shedding purposes. Secured to the shaft 19 is a looper 20 which cooperates with all of the needles to seize and shed the needle thread loops and form a seam similar to that designated type 605 in the Federal Specifications. In the illustrative example, however, this seam incorporates four needle threads instead of three.

g In forming a seam of the 605 type it will be understood ,Within the in. 13 there that a cover thread laying mechanism will be employed, the above-mentioned Smith n such as that disclosedv in patent.

{dog and operating connections for advancing thework Patented Mar. 21, 1961" is provided a four-motion feed 1 longitudinally of the arm and toward the left in Fig. 1. If desired, two feed dogs may be provided, these being arranged to operate differentially in relation to each other. This mechanism may suitably be of the character disclosed in the above-mentioned Smith patent. Cooperating with the feed dog is a suitable presser arrangement including a presser bar 21 mounted for vertical movement Within the head 12. This bar is urged yieldingly downwardly by a spring 22 the force of which may suitably be varied. At the lower end of the presser bar there is carried a presser foot 23 which may be constructed and mounted in the manner disclosed in said Smith patent. It will be understood that the feed dog passes upwardly into cooperation with the presser foot and to enable this an appropriately slotted throat plate 24 (Fig. 3) is provided. To the top face of this throat plate is secured a small plate 25 carrying three stitch fingers. It will be understood that the needles 17 in their movement downwardly through the throat plate will pass between and along the outer side faces of the stitch fingers.

The novel looper thread loop retainer of the present invention is indicated at 26. This is of needle-like form and may be substantially the same as the needles 17 with the omission of the'thread carrying eye adjacent its lower' end and the omission of the longitudinal thread groove provided in the needles 17. Retainer 26 has its upper end mounted in the needle clamp 16 and is retained therein by a set screw 27. The arrangement is such that retainer 26 is disposed in substantially the same plane as the needles 17 and is spaced slightly from the longest. of these. Also, it extends downwardly to a slightly greater extent than the longest needle so as to continue the stepped arrangement of the lower ends of the needles. An opening 28 (Fig. 3) is provided in the throat plate for the passage of the retainer 26 therethrough.

Turning now to Figs. 5-13, inclusive, there is illustrated the mode of operation of the looper thread loop retainer 26. In Fig. 5 the needles 17 and retainer 26 are shown near the lowermost point in their travel, but on their way upwardly to a slight extent therefrom. This upward movement has caused the needle threads 30 to loop outwardly in their portions between the work and the eye of the needle to form loops 30a, 30b, 30c and SOd. The looper 20 carrying a looper thread 31 is shown as just about to enter the loop 30a of the first needle. In Fig. 6 the needles and retainer are shown still moving upwardly while the looper 20 is continuing its loop-seizing movement through the needle thread loops. In Fig. 7 the looper 20 is shown as substantially at the end of its loopseizing movement and the needles are shown approaching their uppermost positions, above the work 29 which is being stitched. Fig. 8 indicates the next step in the cycle. Between the positions of the parts shown in Figs. 7 and 8 the looper 20 will have been given a needle avoid movement to carry its blade from the rear (right) side of the path of the needles to the forward (left) side theremf. Accordingly, as the needles and retainer 26 descend to the position shown in Fig. 8, they will pass rearwardly of the looper blade and enter the several triangles or openings formed between the rear face of the looper blade, the leg or the looper thread which extends from the eye of the latter to the work, and the several loops of.

needle thread. The looper will at this time commence its loop-shedding movement which continues through the portions of the cycle shown in Figs. 9 and 10. It will be noted in Fig. 9 that the needle thread loops are successively being shed from the looper and this operation is completed by the time the parts reach the positions shown in Fig. 10. At this time the needles and retainer have reached the lowermost point in their travels and it will be noted that the retainer 26 serves to hold the looped end 31a of the looper thread spaced from the adjacent needle 17.

As the opposition continues, the looper 20 will be given its opposite needle avoid movement and will commence its new loop-seizing movement. Also, it will be noted that the portion of the looper thread previously passed through the needle thread loops is drawn upwardly by the latter toward the underface of the work and against the undersurface of the stitch fingers of the plate 25. Continued movement of the looper 20 toward the right (Fig. 11) will cause it to seize new loops of needle thread and by the time this step is completed (Fig. 12) the needles and the retainer 26 will be withdrawn from the previous loop of looper thread. This enables the further movement of the looper and the operation of the thread take up mechanism to tighten the stitch against the undersurface of the work and the stitch fingers.

It will be noted that in Fig. 12 that the looped end 31a of the looper thread is just being released by the retainer 26 and it extends a short distance toward the right, thus providing a slight extra amount of looper thread to be incorporated in the stitch. This has been found desirable since it insures more uniform stitch formation and a smoother seam. It prevents the distortion of the stitch which frequently occurs in the operation of machines not equipped with a. retainer such as element 26. The final form of the stitch is indicated in Fig. 13. It will be understood that from this point the completion of the next stitch will continue through the stages indicated in Figs. 7l3, and the stitch forming cycle will then be carried out repeatedly in the same manner to form the desired seam.

In Figs. 14 and 15 there is illustrated the needle thread loop distorting action which occurs on conventional machines not equipped with the looper thread retainer 26. It will be noted that the needle thread loop 30a' in this in stance is prevented from bowing outwardly in the desired manner to receive the advancing end of the looper 20. This is due to the fact that the looped end 31a of the looper thread of the previously formed stitch will grip the needle thread of the right hand needle and tend to twist or choke it or otherwise act upon it to prevent the proper formation of the needle loop 30d. As shown in Fig. 15, this results in the skipping of the needle thread loop 30d so that this will not be properly incorporated in the stitch.

While an illustrative embodiment of the invention and its mode of operation have been disclosed in considerable detail, it will be understood that various changes may be made in the form and arrangement of the several parts within the scope of the invention as defined by the appended claims. Moreover, as hereinabove indicated, the invention is of rather broad application and may be used advantageously in machines having one or more needles cooperating with one or more loopers.

What is claimed is:

l. A sewing machine having a reciprocable needle bar, a plurality of thread carrying needles carried by said bar, a thread-carrying four-motion looper cooperating with said needles to form stitches, means for imparting loop seizing, shedding and needle avoid movements to said looper, said needles having paths of movement spaced along a plane adjacent and parallel with the line of loop seizing movement of the looper, a non-thread-carrying movable loop retainer mounted for movement in the plane of the paths of movement of the needles beyond the last needle from which a loop is seized by said looper, and means for operating the same in properly timed relation to the movement of said bar to cause said retainer to enter the loop of thread carried by said looper in advance of the entry therein of said thread carrying needles and to retain the looped end of looper thread away from said last needle while the looper thread loop is being drawn toward the underface of the work, and while succeeding needle thread loops are being seized by the looper.

2. A sewing machine having a reciprocable needle bar, a plurality of thread carrying needles carried by said bar, a four-motion, thread-carrying looper cooperating with said needles to form stitches, said needles having paths of movement spaced along a plane adjacent'and parallel with the line of loop seizing movement of the looper, and a 'non-thread-carryingmovable loop retainer in the plane of the paths of movement of the needles beyond the last needle from which a loop is seized by said looper and arranged to retain the looped end of looper thread away from said last needle as the looper thread loop is being drawn toward the underface of the work, said loop retainer being mounted on said needle bar for reciprocation therewith.

3. A sewing machine having a reciprocable needle bar, a plurality of thread carrying needles carried by said bar, a four-motion, thread-carrying looper cooperating with said needles to form stitches, said needles having paths of movement spaced along a plane adjacent and parallel with the line of loop seizing movement of the looper, and a non thread-carrying movable loop retainer in the plane of the paths of movement of the needles beyond the last needle from which a loop is seized by said looper and arranged toretain the looped end of looper thread away from said last needle as the looper thread loop is being drawn toward the underface of the work, said loop retainer being a needle-like element spaced from said last needle and parallel therewith and being mounted on said needle bar for reciprocation therewith.

'4. A sewing machine having a frame provided with a work supporting surface, work feeding devices for advancing work along a predetermined line on said surface, a reciprocable needle bar, a plurality of thread carrying needles carried by said bar, a four-motion, thread-carrying looper cooperating with said needles to form stitches, means for imparting loop seizing movement to said looper transverse to the line of feed and for imparting needle avoid movement to said looper in the direction of feed,

' said needles having paths of movement spaced along a plane adjacent and parallel with the line of loop seizing movement of the looper, a non-thread-carrying movable loop retainer in the plane of the paths of movement of the needles beyond the last needle from which a loop is seized by said looper, and means for operating the same in properly timed relation to the movement of said bar to retain the looped end of looper thread away from said last needle as the looper thread loop is being drawn toward the underface of the work.

5. A sewing machine having a reciprocable needle bar, a plurality of thread carrying needles carried by said bar,

a thread-carrying looper cooperating with said needles to form stitches, said needles having paths of movement spaced along a plane adjacent and parallel with the line of loop seizing movement of the looper, and a movable loop retainer in the plane of the paths of movement of the needles beyond the last needle from which a loop is seized by said looper and arranged to retain the looped end of looper thread away from said last needle as the looper thread loop is being drawn toward the underface of the work, said needles having their pointed ends extending stepwise downwardly to progressively greater extents along the line of loop seizing movement of the looperyand said loop retainer being a needle-like non-threadcarrying member mounted for reciprocation with said needle bar adjacent and beyond the need-1e of greatest downward extent and having its lower end extending downwardly further than said last-mentioned needle.

6. A feed-off-the-arm sewing machine having a. frame provided with a work supporting arm and a head extending over said arm, work feeding devices for advancing work lengthwise of said arm, a needle bar reciprocable in said head, a plurality of thread carrying needles carried by said bar and arranged in a plane transverse to said arm, a thread carrying looper in said arm arranged to seize successively the loops of needle thread carried by said needles, and a non-thread-carrying loop retainer adjacent and beyond the last needle from which a needle thread loop is seized arranged to hold the looped end of the looper thread away from said last needle as the looper thread loop is being drawn toward the underface of the work, said loop retainer being a needle-like member carried by said needle bar.

References Cited in the file of this patent UNITED STATES PATENTS 726,310 Klemm Apr. 28, 1903 999,718 Hawes Aug. 1, 1911 1,287,392 ,Molfatt et al Dec. 10, 1918 2,046,928 Riviere et al. July 7, 1936 2,729,176 Smith Jan. 3, 1956 2,812,735 Nelson Nov. 12, 1957 FOREIGN PATENTS 871,874 Germany Mar. 26, 1953 UN :TED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.\. 2,-975,737, March 21, 1961 v Richard H. Lukins It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent. should read as corrected below ERNEST W. SWIDEB Column 3, line 61 for "or" read of -g line 74, fford'opposition read operation Signed and sealed this 21st. day of November 1961.

( SEA L) Attest:

v DAVID L. LADD Attesting Officer Commissioner of Patents USCOMM-DCJ 

